In circuits for conveying fluids under pressure and that implement quick connectors, it is desirable, and often required, to make use of means that lock any connection positively. A completed male connection is firstly a source of leaks and secondly a risk of uncoupling, with the least severe consequence being to put the machine including the pressurized fluid circuit out of order, while if the machine is a car, the consequences can include accidents (no pressure in the hydraulic brake circuits, fuel leakage into the engine compartment possibly leading to a fire,. . . ).
There exist numerous devices for locking the male element in the female element of a quick connector. Substantially all of them operate on the same principle, implementing generally identical means consisting in a keying member which is interposed between a radial surface of the endpiece (groove or collar) and a radial surface of the female element (likewise a groove or a collar). The keying member be inserted manually or it may be held in its locking position by a resilient return member against the effect of which it can be put in a retracted position (either displaced or deformed) during insertion of the endpiece.
In a particularly simple implementation of that device, the lock is constituted by a ring mounted to slide radially in a housing formed in the female part of the connector, between a rest and locking first position in which it is eccentric relative to the axis of the bore of the female part, and a retracted second position in which it is substantially coaxial with the bore.
A resilient member constituted by two tongues integral with the ring is interposed between the ring and the female part and urges the ring towards its first position.
Such a ring is shown in a connector in FIGS. 1 and 2. The drawing shows clearly the relative weakness of such a part at withstanding adequately a large pull-out force. In the connector shown, the female part 1 includes a lock for preventing the endpiece 2 being extracted once it has been properly inserted in the female part 1. The lock is constituted by a ring 3 that can slide radially in the female part 1, in an open housing formed therein, and which includes two outer resilient tongues 4 urging the bore through the ring 3 away from the axis of the bore of the female part 1. The portion of the bore through the ring 3 situated on one side of the tongues 4 is in the form of a surface 5 (e.g. a cylindrical surface) whose axis slopes relative to the axis of the ring, such that when the collar 6 of the endpiece 2 goes past, said surface forms a ramp for moving the axis of the bore through the ring 3 away from the axis of the part 1. The ring 3 can then move against the force of the resilient tongues 4 until the collar 6 is received inside the part 1 beyond the ring 3. The tongues 4 then relax and the ring is back in its free position where it is eccentric relative to the bore in the female part, and one of its flanks comes into contact with the rear flank of the collar 6 and constitutes an abutment opposing extraction of the endpiece 2, since said ring is held axially by the front partition 7 of the female part which possesses an insertion orifice 8 for the male endpiece. On examining the figures, it can be seen that towards the bottom there is little ring material located behind the partition 7. The material is constituted essentially by the tongues 4 since the ring 3 has very little contact area with the partition 7 at the lowest point 5a of the ramp 5. If a large extraction force is applied, then the bottom portion of the ring can deform and penetrate into the orifice 8 while the tabs are locked behind the partition 7. This deformation can be irreversible and lead to the lock being totally destroyed. Any attempt at increasing the thickness of the wall of the ring 3 beneath the ramp 5 to benefit from a larger contact area would require the dimensions of the female part 1 to be completely changed, increasing its overall size for given amplitude of resilient displacement of the tongues 4.